1. Field of the Invention
The present invention relates generally to a tape driving apparatus for use with a magnetic recording and/or reproducing apparatus and is directed more particularly to a magnetic tape driving apparatus in which a capstan is controlled to be driven at a constant speed by a servo motor for the capstan, a speed change of the capstan is detected to control a voltage applied to a reel motor, and hence the tensions of the tape at tape supply and take-up sides are made substantially constant by servo-operation.
2. Description of the Prior Art
In the prior art tape driving apparatus, a supply reel motor coupled to a supply reel and a take-up reel motor coupled to a take-up reel are supplied with a control voltage in response to the tape tension of a magnetic tape detected by a tension arm to make the back and take-up tensions of the tape constant and to apply servo operation to the tape supply and take-up sides, which is constant irregardless of the variation of radii of the tape wound on the supply and take-up reels, whereby the variations of a tape travelling speed and of the head touch against the tape are avoided.
According to the prior art, however, it is impossible to make the back tension and take-up tension equal with each other regardless of any variation of the tape radii of the tape wound on the reels. Therefore, with the prior art the load for the capstan servo motor is varied to cause a speed variation thereof. Further, in the prior art it is necessary to provide a tape tension detector at the tape supply and take-up sides, respectively, so that the apparatus becomes complicated in construction and expensive.